Reversible fluorescent probes for chemical and biological redox process

An overview on recent advances of reversible fluorescent probes and their biological applications

Due to the simplicity and low detection limit, fluorescent probes are widely used in both analytical sensing and optical imaging. Compared to conventional fluorescent probes, reversibility endows the reversible fluorescent probe outstanding advantages and special properties, making reversible fluorescent probes with capable of quantitative, repetitive or circulatory. Reversible fluorescent probes can also monitor the concentration dynamics of target analytes in real time, such as metal ions, proteins and enzymes, as well as intracellular redox processes, which have been widely applied in various fields. This review summarized the types and excellent properties of reversible fluorescent probes designed and developed in recent years. It also summarized the applications of reversible fluorescent probe in fluorescence imaging, biological testing, monitoring redox cycles, and proposed the remaining challenges and future development directions of the reversible fluorescent probe. This review provided comprehensive overview of reversible fluorescent probe, which may provide valuable references for the design and fabrication of the reversible fluorescent probe.

Corrosion behaviors and kinetics of nanoscale zero-valent iron in water: A review

Knowledge on corrosion behaviors and kinetics of nanoscale zero-valent iron (nZVI) in aquatic environment is particularly significant for understanding the reactivity, longevity and stability of nZVI, as well as providing theoretical guidance for developing a cost-effective nZVI-based technology and designing large-scale applications. Herein, this review gives a holistic overview on the corrosion behaviors and kinetics of nZVI in water. Firstly, Eh-pH diagram is introduced to predict the thermodynamics trend of iron corrosion. The morphological, structural, and compositional evolution of (modified-) nZVI under different environmental conditions, assisted with microscopic and spectroscopic evidence, is then summarized. Afterwards, common analytical methods and characterization technologies are categorized to establish time-resolved corrosion kinetics of nZVI in water. Specifically, stable models for calculating the corrosion rate constant of nZVI as well as electrochemical methods for monitoring the redox reaction are discussed, emphasizing their capabilities in studying the dynamic iron corrosion processes. Finally, in the future, more efforts are encouraged to study the corrosion behaviors of nZVI in long-term practical application and further build nanoparticles with precisely tailored properties. We expect that our work can deepen the understanding of the nZVI chemistry in aquatic environment.

Advances in organic fluorescent probes for bromide ions, hypobromous acid and related eosinophil peroxidase-A review

Elemental bromine is among the essential elements for human health. In living organisms, bromide (Br^-) and hydrogen peroxide (H₂O₂) can be catalyzed by eosinophil peroxidase (EPO) to generate a reactive oxygen species (ROS), hypobromous acid (HOBr), which exhibits properties similar to those of hypochlorous acid (HOCl). Moreover, HOBr possesses strong oxidative and antibacterial properties, which are believed to play an important role in the neutrophil host defense system. However, overexpression or misexpression of HOBr can cause organismal and tissue damage, which is closely related to the development of various diseases. Therefore, an increasing number of studies has demonstrated physiological associations with the conversion of Br^- to HOBr. With the development of fluorescence imaging technology, developing fluorescent probes with novel structures and high selectivity to detect changes in Br^-, HOBr, and the related enzyme EPO levels in organisms has become very important. This paper summarizes Br^-, HOBr, and EPO fluorescent probes reported in recent years, including the design principles, mechanisms, optical properties, and bioapplications. Finally, the application prospects and challenges are also discussed.

A novel DCM-based NIR fluorescent probe for detecting ozone and its bioimaging in live cells

Nowadays, ozone has been widely applied in industry and medical therapies. However, excessive exposure to ozone can lead to lung dysfunction and many respiratory symptoms. As a member of reactive oxygen species (ROS), ozone was also involved in various physiology and pathology process. Given the fact of this, the effective detection of ozone in the atmosphere and biological system is of vital significance. Herein, we reported a novel dicyanomethylene-4H-pyran (DCM)-based fluorescent probe DCM-O₃ with butenyl being the recognition moiety for monitoring ozone. The probe displayed high selectivity towards ozone, and its response towards ozone could be completed within 5 min under the optimal condition. Besides, a good linear correlation was obtained between the ozone concentrations (0-50 μM) and the corresponding fluorescent intensity at 560 nm, and the limit of detection (LOD) was calculated to be 6.2 × 10^-7 M. Moreover, the probe DCM-O₃ showed low cytotoxicity and was successfully applied to detect ozone in live cells. Given all the merits, the probe DCM-O₃ could function as a robust tool for researchers to investigate ozone-related diseases in the complex biological environment.

Photoexcited molecular probes for selective and revertible imaging of cellular reactive oxygen species

Redox homeostasis is key to maintaining the normal physiological status of living cells.

Depletion of protein thiols and the accumulation of oxidized thioredoxin in Parkinsonism disclosed by a red-emitting and environment-sensitive probe

Protein sulfhydryl groups play a vital role in maintaining cellular redox homeostasis and protein functions and have attracted increasing interests for the selective detection of protein thiols over low-molecular-weight thiols (LMWTs).

Small-molecule luminescent probes for the detection of cellular oxidizing and nitrating species

Reactive oxygen species (ROS) have been implicated in both pathogenic cellular damage events and physiological cellular redox signaling and regulation. To unravel the biological role of ROS, it is very important to be able to detect and identify the species involved. In this review, we introduce the reader to the methods of detection of ROS using luminescent (fluorescent, chemiluminescent, and bioluminescent) probes and discuss typical limitations of those probes. We review the most widely used probes, state-of-the-art assays, and the new, promising approaches for rigorous detection and identification of superoxide radical anion, hydrogen peroxide, and peroxynitrite. The combination of real-time monitoring of the dynamics of ROS in cells and the identification of the specific products formed from the probes will reveal the role of specific types of ROS in cellular function and dysfunction. Understanding the molecular mechanisms involving ROS may help with the development of new therapeutics for several diseases involving dysregulated cellular redox status.